Embodiments of the inventive concepts described herein relate to a vertically-integrated 3-dimensional flash memory, and more particularly, relate to a 3-dimensional flash memory capable of improving a cell reliability of the vertically-integrated 3-dimensional flash memory using a macaroni layer having a high thermal conductivity and a method for fabricating the 3-dimensional flash memory.
As the size of digital data, such as photos, videos, and audios, increases exponentially, demands for a non-volatile storage medium keep on increasing. A flash memory is a typical non-volatile memory that is currently being commercialized and mass-produced and is rapidly replacing a hard disk.
For operation of the non-volatile memory, the flash memory includes a charge storage layer, such as a nitride material forming a floating gate or an oxide-nitride-oxide (ONO) structure, disposed between gate insulating layers. The non-volatile memory operates based on a principle where electrons injected into the charge storage layer are stored by a Fowler-Nordheim Tunneling phenomenon or a hot-carrier injection phenomenon, which is generated by voltages applied to a gate and a source/drain.
Since demands for a data storage increases due to the spread of smart devices, an integration degree of the memory in the same flash memory chip size starts to increase. To improve the integration degree, a maximum number of cells is required to be integrated in the chip. One cell stores 1-bit data, 2-bit data (MLC), 3-bit data (TLC), or the like, and recently, 4-bit (QLC) technology is under development.
Until now, the cell of the flash memory is fabricated through a fine process in a two-dimensional (2D) plane to improve the integration degree. However, various problems, such as intensifying a short-channel effect of a cell transistor, intensifying a cell disturbance between different word lines, increasing a manufacturing cost and technical limitations due to a minimum line width process, or the like, occur as a size of the cell (or a gate length) is reduced. Due to the above problems, improvement in integration degree and driving reliability of the flash memory is close to its limit, and to solve this, a vertically-integrated 3-dimensional flash memory (3D V-NAND) cell technology has been newly suggested.
The present inventive concept suggests a way to effectively dissipate heat generated when the flash memory operates in the vertically-integrated 3-dimensional flash memory to a substrate.